The firewood today is still the only renewable fuel available in our surroundings in large quantities. Usually it produces few ashes. Moreover the combustion of wood doesn’t create slags.

Wood is composed of 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen and 1% of mineral matter. Its big content of oxygen explains why wood is a fuel that needs little oxygen to burn.

The calorific value of wood varies along with its substances, some are more powerful than others. Hedge beech, oak wood, leafy trees are ahead. The table classifies the various woods in our regions.

Coefficient 10 corresponds to that which gives the most heat per m³. The calorific value of wood varies with to the degree of humidity it contains.

The drier the wood, the bigger the release of heat. The period of drying and how the wood was treated is of importance. Wood that has been cut 18 to 24 months prior is ideal. Freshly cut wood contains approximately 75% water. This is likely to cause the formation of tar in the smoke with all the problems that entails.

The consumption and the wear of a hearth vary considerably with the frequence, the level of use of the hearth and maintenance. Thus, these parts of the hearth are prone to wear: the grille, the bottom, the sides, the deflector, the hinges and the door.